The authors developed an apparatus for experimenting on desulphurization in the blast furnace. It was pointed out that the process hitherto used of causing SO₂ or H₂S to react on iron or coke was unsatisfactory; and it was clarified that the effect of combustible sulphur in coke on desulphurization was small if that of the sulphur in the bosh gas on the molten pig iron was small, because, in the blast furnace shaft, the sulphur in iron ore and coke was removed by the ascending gas and the sulphur removed there at 1, 000°C escaped more into gas than into lime stone.
As regards the effect of bosh gas in the bosh on molten pig iron, the authors considered that studies should be made further.

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To clarify the effect of MgO on the viscosity of blast furnace slag, viscosities of synthetic CaO-SiO₂-Al₂O₃-MgO slags were measured by the rotating inner-cylinder viscosimeter as in the case of the first report. (Tetsu-to-Hagane, Vol. 38, 1952, 12) Iso-viscosity lines at 1, 500 and 1, 600°C are drawn on the diagram (Fig. 1, 2, 3)
When MgO was added to GaO-SiO₂ slag, the viscosity decreased with increasing amounts of MgO up to about 20%, but thereafter increased. The region of low viscosity in Cao-SiO₂-MgO slag was greater than that in the CaO-SiO₂-Al₂O₃ slag.
When MgO was added to CaO-SiO₂-Al₂O₃ slag, the viscosity decreased and moreover changein viscosity at constant temperature caused by the change of slag composition became small, but these beneficial effects of MgO were less noticeable than those reported by the previous investigator. With respect to the fluxing quality, MgO had nearly as much influence in reducing slag viscosity as CaO or slightly less.

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Using a CaO crucible, authors measured the equilibrium the following reaction under the conditions of 2CaO·SiO₂, 3CaO·SiO₂ or CaO saturation at the temperatures of 1550° and 1700°C,
At the reaction (1), the equilibrium constant became as follows.
Further, as already published in the first report, the reaction and the equilibrium constant at the system, saturated by SiO₂ were given respectivelly as follows.
If the activity of pure SiO₂ was taken to unity as the standard state of α_SiO2, K and K^s ought to be equal at a given temperature, thus, α_SiO2 in the slag of SiO₂-CaO-Al₂O₃ system was calculated from following equation;
Finally, authors determined the liquidus at the temperatures of 1550°C and 1600°C on the CaO side of SiO₂-CaO-Al₂O₃ ternary diagram from equilibrium compositions of slag.

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Investigation was made on the characteristics and cause of mechanical surface defects which occurred in low carbon steel bloom and on their prevention. The results of this investigation were summarized as follows:
1. The mechanical surface defects were classified into 14 kinds under the following 6 categories: (A). those caused by rugging…4 kinds (B). those caused by roughness of roll surface…2 kinds (C). those caused by abnormal compression…2 kinds (D). those caused by inclusions compressed into blooms…2 kinds (E). those caused by accessory equipments of rolls 2 kinds (F). those which occur at the time of materials being under working…2 kinds
2. Defects which came under the categories of A and B had mainly their causes in rough rolling.
3. The mechanism of causing each kind of defects and its prevention were stated.
4. It was recommended that rugging should be practised so as to be parallel to the roll shaft and be linear.
5. Comparatively high temperature of materials rolled was favorable for preventing the occurence of defects.
6. If reasonable rugging is applied to rolls, rolling of materials at the first stage in using the rolls was favorable for preventing the occurence of defects.
7. Slower rolling was better than speedy rolling for preventing the occurence of defects.
8. A consideration was experimentally given on the irregularity of surface defects of rolled products.

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The various decarburized layers resulted from different decarburizing treatments were carburized in the modified town gas, and following results were obtained:
(1) The carburizing power of the modified gas containing CO 20%, CH₄ 5%, H₂ 54% and N₂ 20%, was weaker than that of charcoal+BaCO₃ 20%. In the carbon restoration by the modified gas as well as by the common solid carburizer, both depth and amount of carburization were larger in specimens of non-oxidizing decarburization than those in specimens of oxidizing decarburization.
(2) In the carbon restoration by the modified gas, the carburization was not accompanied with the oxidation as in the case of the common solid carburizer.
(3) In the carbon restoration by the modified gas, both depth and amount carburization in specimens of oxidizing decarburization approached to those of non-oxidizing decarburization specimens with the increase of the carburizing time. It was presumably explained by the fact that carburization of the decarburized layer formed by the oxidizing decarburization was accompanied. by reduction of the oxygen in the decarburized layer and the diffusion of carbon through these layers becomes easier.

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To obtain the low cost and high resistant steel for mixture gases in ammonia synthesis, the author studied on the effect of hydrogen and nitrogen at pressure 650atm and temperature 550°C on the same kinds of steel as in the 2nd report. (Lect. Meet. Iron & St. Inst. Japan, Apr. 1951) The author inserted the specimens in catalyst bed for 491 hours, and exposed them to high pressure and temperature mixtures. After exposure, the author tested them by the same method as in the former report. The main results obtained were summarized as follows:
1) In the Casale Plant, attacks of nitrogen were very important as the same degree as in the Claude Plant.
2) Chromium containing steel always had cracks by mixture attacks, but in case chromium content increased as much as 5 percent, the availability of chromium in steel was recognized for the first time.
3) Nickel was the useful alloy element because of its crack-proof properties just like in the previous report.

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Influence of phosphorus and silicon on the mechanical properties of spheroidal graphite cast iron was reported. Pure magnesium (0.5% Mg) was introduced to the molten metal which had been prepared from Swedish iron, ferro-silicon and ferro-phosphorus, inoculated with 0.4% Si and poured to the keel block dry sand mould. Tensile and impact tests were carried out in the ascast condition and the as-annealed condition.
In the as cast condition, the following properties were obtained; tensile strength 55 to 75kg/mm₂, elongation 0.4 to 7.4%, Charpy impact strength (without notch) 0.3 to 4.7mkg. The structure of matrix was substantially pearlitic, where a small amount of ferrite could be observed. The tensile strength gradually decreased with increasing of phosphorus content, but the elongation and Charpy impact strength decreased rapidly.
In the as annealed condition, very good ductility was obtained when both phosphorus and silicon content were low. Generally the tensile strength slightly increased with increasing of phosphorus up to 0.12%. More of this amount of phosphorus caused the phosphide structure to appear, which decreased the tensile strength gradually and impact strength rapidly.
Silicon had also the important effect on toughness of the spheroidal graphite cast iron.
It was shown that 0.15% phosphorus had no appreciable effect on the elongation and impact strength of the spheroidal graphite cast iron with 2.0% Si, but the same amount of phosphorus had embrittling effect in the iron with 3.0% silicon.

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Three kinds of rods employed as samples in this experiment, were rods for card-clothing-wire, and piano-wire, and rope-wire. They were made in Japan, Sweden, England, Belgium, Switzerland, France, and U.S.A. The samples were dissolved in H₂SO₄ (1:5) by warming on water bath with taking precaution against rising of the temperature of acid above 90°C, and black residues thus produced were compared with each other. It was found that the quantities of the residues were different from each other, although the steel rods had the same carbon content, and the residues of Japanese rods were larger in quantity than those of foreign rods.
For examples, the composition of some rods were as follows: C 3.6-5.0%, Si 3.36-10.47%, Mn 0.39-0.63%, S 0.31-0.39%, Ni 1.57-1.96%, Cr .0%, Cu 6.23-14.62%, and Fe 28.3-45.3%. Most part of carbide, silicon compound, sulphide and nicke], almost all parts of metallic iron and manganese compound, all part of Cr were dissolved but all part of copper remained undissolved.

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The effects of cooling (air cool and water cool) of the same vacuum vessel of the furnace of a carbon spiral resistor type, constructed to have high evacuation velocity, for the gas analysis of several sorts of Standard steel specimens, were studied. It was recognized that diminishing effects by evaporization of Mn or Al on the oxygen and the nitrogen values of the specimens were strengthened by strong cooling of the vessel, and that effects caused by previously condensed film of the Mn or the Al on the nitrogen values were rather increased by the hot vacuum vessel. The former effects were considered to be caused by pile of physical gas adsorption by condensation of the Mn or the Al every moment, and the latter by the chemical reaction or nitride formation of the condensed Mn or Al. In order to decrease both effects, the temperature of the vacuum vessel and the parts of condensed film of evaporizing materials must be mentained in adequate range.

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The Ms temperatures of high-carbon steels containing 1.07, 1.16 or 1.25%C quenched from the temperature range at which austenite and cementite coexist were measured by the quench-temper procedure of Greninger and Troiano (T.A.S.M. 28 (1940) 537).
The results obtained were as followg:
(1) With increasing of austenitizing temperature, Ms point is lowered markedly and gradually approaches to the constant temperature when austenitizing temperature rise beyond Acm line.
(2) The steels having globular pearlitic structure before the austenitizing, showed slightly higher Ms points than those of steels having lamellar pearlitic structure, but the difference was small and diminished with increasing of both austenitizing temperature and heating time.
(3) The Ms temperatures seems to depend on the carbon content of austenite, but not on the amount of coexisting cementite.
(4) The Ms temperatures for practical quenching of the high-carbon steels used in this study are about 240°C, and are much higher than those for quenched steels from the temperature range of austenite only.

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In the previous report, (Tetsu-to-Hagane, 38, 1952, 37-40) the authors made clear the effect of carbon on the high carbon high chromium die steel containing high chromium. In the present investigation, the authors studied the effect of chromium on the high carbon high chromium die steels by the same method as previous investigation.
As the results of these investigations, the authors found most moderate composition of die steel, eoncluding that 10-12% chromium content in die steel containing 2.1-2.2% carbon was better as the punching dies and then 12% or more chromium content was better as the drawing dies.

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